The present invention relates to a bleed system for extracting turbine cooling air from a compressor stage of a turbine engine.
In order to ensure sufficient pressure differential to drive a bleed flow, bleed ports are located aft of a vane trailing edge where the static pressure, which increases with axial distance, is highest. However, in the vicinity of the vane trailing edge, the gas path air has little or no tangential velocity. As a result, the air introduced into an annular cavity radially inboard of the vane platform is accelerated to compressor wheel speed by the compressor disks that axially bound the annular cavity. The acceleration of the air in the annular cavity elevates the air temperature, which is highly disadvantageous from the standpoint of component cooling and engine efficiency.
It is an object of the present invention to provide a bleed system which takes advantage of the tangential velocity component of the air coming off the trailing edges of upstream blades to avoid a temperature rise.
It is a further object of the present invention to provide a bleed system as above which improves engine efficiency.
The foregoing objects are attained by the bleed system of the present invention.
In accordance with the present invention, a bleed system for a compressor stage of a turbine engine is provided. The bleed system broadly comprises a plurality of blades with each of the blades having an airfoil member extending from a platform structure, a plurality of interblade passages formed by adjacent ones of the airfoil members and adjacent ones of the platform structures, and a bleed hole located in at least some of the interblade passages for extracting a portion of a fluid flowing through each interblade passage. The system further has means for tangentially injecting the extracted air in a direction of rotation.
The invention also relates to a component for use in a turbine engine. The component broadly comprises a blade having an airfoil member with a pressure side and a suction side. The blade further has a platform structure and a bleed hole in the platform structure.
Other details of the bleed system of the present invention, as well as other objects and advantages attendant thereto, are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.